The present invention, in some embodiments thereof, relates to a dual component applicator and, more particularly, but not exclusively, to a dual component applicator for mixing substances to produce a cementitious substance.
A cementitious substance used to treat bones and/or teeth of a patient is produced by mixing a pre-cementitious substance in powder form with a liquid carrier. As the time from mixing to hardening of the cement is fairly short, the cement needs to be mixed right before the procedure takes place.
The cementitious substance is used to repair bone and/or teeth defects, for example, by bone implantation, bone augmentation, and/or as a bone graft. Defects may result from bone and joint operations such as, for example, orthopedics or maxillofacial surgery including surgical removal of cysts, foci of suppuration and malignant bone tumors. These medical procedures may result in voids, gaps and other bone defects. Other examples of bone defects include those resulting, for example, from compression fractures, high-energy trauma, peri-articular fractures, cranial-maxillo facial fractures, osteoporotic reinforcement (i.e. screw augmentation) and periodontal reconstruction.
Dentistry is an exemplary field in which repairing bone defects may be necessary optionally in addition to dental implants, for replacing missing teeth. When a person experiences teeth loss due to trauma or other circumstances, or suffers from periodontal disease, loss of interproximal crestal alveolar bone is one of the conditions which the practitioner may deal with. This bone loss may further result in the loss of a person's interproximal or papillary oral tissue between the corresponding teeth and may cause a bone defect that is very unappealing aesthetically, as well as difficult to restore. Without the proper regeneration of this bone defect, any replacement tooth is likely to be mal-positioned, out of proportion, shape and form, and lack interproximal tissue for a natural appearance.
The cementitious material may also be used, for example, to provide osteogenic (bone forming), osteoconductive (providing an inert scaffold on which osseous tissue can regenerate bone), and/or osteoinductive (stimulating cells to undergo phenotypic conversion to osteoprogenitor cell types capable of formation of bone) properties.
The cementitious substance is shaped so as to fill the bone defect as desired. Shaping the cementitious substance may be achieved by hand or by means of a shaping tool such as a spatula, a spoon, a broad flat blade and the like.
The simplest way to mix the pre-cementitious substance and the liquid carrier is by manually mixing on a plate. However, the plate mixing method is extremely prone to contamination. Sterility is important, as the cement is inserted into the body of a patient. Furthermore, the plate mixing method is prone to error, as precise measurements of the pre-cementitious substance and the liquid are required to produce the correct cement.
Yahav, in International Patent Application Publication No. WO2009104187 discloses “. . . applicators for applying flowable mixtures formed by mixing a dry composition and a liquid carrier, which are particularly useful for preparing and applying bone graft compositions . . . ” Yahav teaches an applicator preloaded with a predefined amount of the pre-cementitious material. When it is time to form the cement, the operator draws water into the applicator to activate the composition and form the cement. When the cement has been mixed enough, it is removed from the applicator. Use of the applicator requires training and experience by the operator; to ensure that the correct amount of fluid is drawn in, to judge how much to mix the substances, and how long to wait until the substance is ready for removal. Furthermore, keeping the liquid sterile until it is withdrawn into the applicator is problematic.
Szwarc, in U.S. Pat. No. 4,613,326 discloses a device for mixing a liquid carrier and a powder to form a liquid medicine for injection into a patient; “A two-component syringe assembly . . . . The barrel also includes a bypass defining a bypass zone positioned along the barrel for allowing fluid to flow around the bypass stopper when the bypass stopper is positioned intermediate the ends of the barrel in the bypass zone . . . . The barrier flange projects outwardly from the body portion into the space between the inside wall of the barrel and the outside of the body portion for acting as a barrier for blocking the path of fluid which may be propelled in a distal direction through the bypass when the syringe is being operated.”
Szwarc attempts to solve the problem of maintaining sterility, by mixing the components within the syringe itself. The bypass zone allows the liquid to travel forward to mix with the powder. However, while injecting the medicine into a patient, medicine and blood are blown back towards the operator through the bypass zone. Therefore, on the one hand, the bypass zone needs to be made as small as possible to prevent the operator from being contaminated with the medicine and blood. On the other hand, the bypass zone should be made larger to ease the mixing process.